Generally, within the field of manufacture and assembly of circuit boards, electronic components are fed to a component mounting machine for mounting the components onto a circuit board. The components can be provided in various ways, such as in component tapes, bulk containers or component tubes. In the latter, components are consecutively stored in elongated, generally plastic tubes. The tubes are generally arranged with open ends that are plugged during shipping and storage. In operation, at least one of the plugs are removed, and the component tube is inserted with the open end first into a component mounting machine, or more commonly into a magazine for use in a component mounting machine. Such a magazine is provided with vibratory feeding means, which brings about a motion of the component tube resulting in a feeding of the components contained therein, out of the open end thereof towards a picking position in the mounting machine. The picking position is determined, in the feeding direction of the components, by the size of the component and by a component stop arranged in a component receiver or positioner which is provided near the open end of the component tube and which restricts the further forward feed of the component. Thus, the dimensions and position of the component receiver determine the longitudinal, i.e. in the feeding direction, picking position for the component to be picked.
In the simplest case, the so called vibratory feeding means could simply provide a vibration which, sometimes in combination with a tilting of the component tube, results in components practically being shaken out of the tubes towards the picking position. However, the so called vibratory movement is generally a very quick reciprocating movement feeding the components forward within and out of the tubes. In theory, the components and the component tubes are brought forward together during the forward moving portion of the reciprocating movement, but only the component tube is brought back during the backward moving portion of the reciprocating movement. In practice, the components experience a backward movement as well, but the component tube is brought back more than the components during the backward portion of the feeding movement, thereby producing the forward feed of the components. Since the movement can be so fast and the length of stroke so short, the reciprocating movement is often not discernable to a human eye, and such feeding is therefore generally referred to as vibration or vibratory feeding, whether it is a carefully controlled reciprocal movement or a lesser controlled vibration.
Prior to the vibratory feeding of components towards the picking position in a component mounting machine, a plurality of component tubes, holding components to be used in the ensuing mounting process, are loaded into a component magazine, which generally is provided with vibratory feeding means. Component mounting machines require that a component that is to be picked is positioned at a well defined picking position, known or identifiable by the mounting machine software. Thus, following loading of the component tubes in prior art component mounting machines, the position for picking the components being fed out of the tubes is determined.
Generally, the picking positions for components from a plurality of laterally adjacent component tubes are preferably located along an essentially straight line. This is particularly important for a split-axis machine where the pick-up head is arranged for general movement in one direction during picking and placing, generally the lateral or X direction, while the positioning in the direction perpendicular thereto, generally the longitudinal or Y direction, during placement is provided by moving the circuit board. However, it is also applicable to a mounting machine in which the pick-up head moves in both the X and Y directions during picking and placing. Since the components are often of different sizes and are preferably picked at the longitudinal and lateral centre of the component body, the picking positions in the feeding directions are adjusted by varying the positions of the component stops, such that an alignment essentially along said straight line is obtained. In practice, the position of the component receiver may be adjustable, e.g. by means of a fastening screw which extends through a slit of the component receiver into a fixed seat in a magazine. Additionally, the alignment of picking positions is performed by providing a number of different component receivers, having different longitudinal and lateral dimensions, which are mounted to the component magazine, generally by screw mounting. Then, one component receiver is generally provided for each component tube.
After loading the component tubes and mounting the component receivers in and to a magazine and loading the magazine into a component mounting machine, i.e. before mounting can begin, a manual locating operation is performed as follows. A camera or other vision device provided in the component mounting machine generates an image of the area in the vicinity of the picking position. For each component tube, an operator, guided by the image generated by the camera, carefully moves the camera to the correct picking position for the first component fed from a component tube. The operator then indicates the accurate picking position to the machine software, i.e. generally at the longitudinal and lateral centre of the component body. Since the possibility of post-picking adjustment of the pick-up head in order to compensate for a component being out of position at the picking position is limited, it is often desirable to reduce the offset of the picking position, in particular any offset in the Y-direction in a split-axis machine. Therefore, the locating operation performed by the operator often includes a position adjustment of the component receiver as well, in order to align the component to a desired picking position.
As realized from the above, the loading of component tubes to a component mounting machine before feeding and mounting of components can commence is a time-consuming and sometimes complicated process. This process has to be performed every time a new type of component is added to the circuit board manufacturing process, and every time an empty component tube has to be replaced. This negatively affects the overall time efficiency of the manufacturing process and, hence, the overall costs.